Safety device for manhole covers



April 17, 1934. c. E. REGO 1,955,018

SAFETY DEVICE FOR MANHOLE COVERS Filed Feb. 2, 1933 q Fig.3. a) 3 o 971%,L 231' venior:

ab 5'0 '30 CMTMERsgg/ H L l i 6-1345 64:; (5 131; @WWM Patented Apr. 17,1934 UNITED STATES PATENT OFFICE 2 Claims.

This invention relates to safety devices for manhole covers andparticularly for the covers of manholes in which gases are liable toaccumulate and cause an explosion when an electric current thereinbecomes short circuited.

One object of the invention is to limit the upward movement of the coverwhen an explosion occurs within the manhole.

Another object is the provision of means for designating in a servicestation the particular manhole in which an explosion has occurred.

These objects are attained by the mechanism illustrated in theaccompanying drawing.

v For the purpose of illustrating the invention,

one preferred form thereof is illustrated in the drawing, this formhaving been found to give satisfactory and reliable results, although itis to be understood that the various instrumentalities of which theinvention consists can be variously arranged and organized, and theinvention is not limited to the precise arrangement and organization ofthese instrumentalities as herein shown and described except as requiredby the scope of the appended claims.

' Of the drawing Figure 1 represents a plan of a manhole seat and covertherefor.

Figure 2 represents a vertical section of same on line 2, 2, on Fig. 1,and

Figure 3 represents a diagram showing a plurality of manholeselectrically connected to an annunciator in a service station.

Similar characters indicate like parts throughout the several figures ofthe drawing.

In the drawing, represents an annular seat having a depression 11therein to receive a man hole cover 12.

The cover 12 is adapted to close a manhole 13 which has recesses 14formed in the side wall 40 thereof.

In each one of these recesses 14 is disposed a tubular member 15, theupper end of which is secured to the annular seat 10.

Each tubular member 15 has a partition 16 therein and the lower end ofeach tubular member 15 is provided with a closure 17.

Above the closure 17 and below the partition 16 is a piston 18 adaptedto reciprocate endwise of said tubular member 15.

Between the partition 16 and piston 18 is a helical spring 19 and justbeneath each partition 16 is a filling plug 20.

By removing this filling plug 20 the space between the partition 16 andpiston 18 may be filled 5 with alemite or some similar lubricant, thislubricant keeping the spring 19 and piston 18 in workable condition atall times.

The piston 18 is threaded to the lower end of a rod 21 extendingupwardly through the partition 16 and having at its upper end a headednut 22 extending through the cover 12, the head of each nut 22 beingdisposed in a depression 12 in said cover.

The piston 18 may be adjusted lengthwise of the rod 21 to vary thetension of the spring 19 and then locked in adjusted position by meansof the nuts 23, 24.

The closure 17 may be adjusted to vary the downward movement of the rod21.

Surrounding each tubular member 15 are a plurality of anchors 25extending outwardly between the bricks forming the walls of the manhole,thereby preventing any upward movement of the tubular member 15, thesetubular members 15 having been disposed within the recesses 14 formed inthe wall of the manhole.

The recesses 14 are closed by concrete 14 leaving the cylindrical wallto the manhole free from all protuberances extending into the manhole.

This is of some advantage as it prevents any injury to the workmenwithin the manhole.

One of the tubular members 15 is provided with a switch 26 which may beof any well known construction and includes a movable member 27 in thepath of a disk 28 secured to the rod 21.

This switch 26 is in an electric circuit 26 provided with a battery 29and has a signal such as a lamp 30 in the circuit.

When an explosion takes place within the manhole, the cover 12 will beraised from its seat 10 a limited distance, the springs 19 beingcompressed during this upward movement of the cover 12.

During the lifting of the cover the gas within the manhole will escapeand then the springs 19 will return the cover 12 to its normal position.

During the lifting of the cover 12 the disk 28 will operate the movablemember 27 of the switch 26 and close the electric circuit 26 to thesignal lamp 30.

This lamp 30 may be located at any convenient point as in a servicestation.

Preferably the lamp 30 is one of a plurality of lamps on an annunciator31 and each lamp on the annunciator is electrically connected with adifferent manhole safety device.

By means of this construction whenever an explosion occurs in anyparticular manhole, a warning is given in the service station and theparticular manhole in which the explosion occurs is indicated on theanmmciator 31.

By this system the service station is warned whenever an explosionoccurs and identification is made as to the particular point where thetrouble occurs.

By use of this system the service man can quickly get to the point wherethe trouble has occurred and make the necessary repairs.

When access is desired to the interior of the manhole, the headed nuts22 threaded to the upper ends of the rods 21 may be removed and thecover 12 displaced from its seat 10.

The cover 12 has laterally extending projections 32 which rest inrecesses 33 in the seat 10 and when these projections 32 are positionedwithin the recesses 33 the nuts 22 will always be in register with therods 21 within the tubular members 15.

The switch 26 is so constructed that, when once closed by the upwardmovement of the disk 28, it will remain closed until the service menreach the manhole 13 and make the necessary repairs, it being thenreturned to its normal position by one of said service men.

It is believed the operation and many advantages of the invention willbe understood readily without further description.

Having thus described my invention, I claim 1. In a device of the classdescribed, the combination of a manhole cover; an annular seat therefor;a plurality of tubular members depending from said seat, each having apartition therein; a piston beneath said partition; a rod to which saidpiston is connected, the upper end of said rod being connected to saidcover; and a spring surrounding said rod between said partition andpiston.

2. In a device of the class described, the combination of a manholecover; an annular seat therefor; a plurality of tubular membersdepending from said seat, each having a partition therein; a pistonbeneath said partition; a rod to which said piston is connected, theupper end of said rod being connected to said cover; and resilient meansbetween said partition and piston.

CHARLES E. REGO.

